That would definitely not be worth it
At one point, 928 Motorsports had a high output alternator and Pelican resells a lot of their stuff. It was about $1k, and was basically just a Mechman 6G small case alternator with a custom case to fit the 928. Supposedly, the 6G small case alternators don't handle high RPMs as well as the large case alternators, but I don't have first hand experience with that.
They might still have that available, if you're looking for true plug and play.
Let us know which route you end up going. Feel free to drop me a line if I can help.